Excellent link! I succeeded in eliminating sugar, getting my gut back in shape [this was years and years ago; I’ve since fallen], and I felt like a million bucks. Correct diet and exercise [and drinking purified water!] s-o-o-o-o important.......
Thanks again for the link [gotta get back on track]; here it is once more!
https://www.google.com/search?q=gut+microbes+obesity&ie=utf-8&oe=utf-8
I am trying to do those same things, and started taking 5000 IU of D3 when I was surprised to find my level was borderline low.
The guy who wrote Grain Brain has a book out this year called Brain Maker about gut microbes and your brain - it makes a lot of sense. He (Dr. Pearlmutter) is also a big Vit D proponent!